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Sediment transport in a small stream based on 137 Cs inventories of the bed load fraction

1990; Wiley; Volume: 26; Issue: 6 Linguagem: Inglês

10.1029/wr026i006p01177

1944-7973

Robert W. Sobocinski, Thure E. Cerling, Stan J. Morrison, Ingvar L. Larsen,

Hydrology and Watershed Management Studies

We report on sediment transport in White Oak Creek, a small third‐order stream in eastern Tennessee, whose sediments have been contaminated by the irreversible adsorption of 137 Cs. Sediment cores taken downstream from a point contamination source record the recent history of sedimentation and contamination in the creek. Sediment size distinguishes between different sedimentation events. The contamination profile developed since the last sedimentation event is used to estimate the time of the most recent sedimentation event which agrees with higher‐than‐normal periods of discharge measured by weirs on the creek. It is likely that at least seven major bed load transport events occurred during 1985 and 1986. Total inventories of 137 Cs in the bed load fraction were measured for six different size fractions for cores taken downstream from the point contamination source. The 137 Cs concentration at any point in the creek is due to contaminated sediment transported to that location and subsequent contamination by 137 Cs adsorbed directly from stream‐water. The irreversible nature of 137 Cs adsorption onto the sediments of White Oak Creek means that 137 Cs can be used as a particle tracer in this system. Sediment transport in White Oak Creek was modeled by using a general transport model that has terms for dispersion, velocity, adsorption, and radioactive decay. For White Oak Creek, maximum velocities of 265, 215, 170, and 160 m y −1 are estimated for the 1–2, 2–4, 4–8, and 8–16 mm size fractions, respectively.